G2 Geomagnetic Storm Hits Earth on October 4: Coronal Hole Wind Outruns the Forecast, Auroras Across the Northern U.S.

Earth's magnetic field reached G2 (Moderate) geomagnetic storm level on Sunday, October 4, at 4:57 PM ET, NOAA's Space Weather Prediction Center reported, after a fast stream of solar wind from a coronal hole on the sun hit Earth and pushed the planetary K-index to 6. The storm, stronger than the G1 (Minor) level NOAA had forecast, brought auroras to the northern tier of the United States on Saturday and Sunday nights. NOAA expects conditions to ease through Monday and return to quiet by midweek.

What NOAA reported

The alert (Space Weather Message Code ALTK06, serial number 726) was issued at 4:58 PM ET on October 4. It came at the end of a long run of warnings: NOAA first flagged Kp 4 at 2:13 AM ET on Sunday, raised the warning to Kp 5 (G1) at 7:07 AM, and extended both warnings into the evening before the Kp 6 threshold was reached at 4:57 PM. Two more G1 alerts followed overnight, the last at 11:52 PM ET on October 4 (3:52 UTC October 5), as the storm faded back toward minor levels.

NOAA's forecast discussion issued at 8:30 PM ET on October 4 names the cause: a positive-polarity coronal hole, a region of the sun's outer atmosphere where the magnetic field opens into space and lets the solar wind escape faster. The stream's effect was unusually strong for a coronal hole. Solar wind speed climbed from about 300 km/s to a peak of about 644 km/s at 2:07 PM ET, the total interplanetary magnetic field strength rose to 22 nT, and its north-south component swung as far as -20 nT southward at 2:11 AM ET. A southward field is what lets the solar wind couple into Earth's magnetosphere, which is why Sunday's storm outran the forecast.

This was not the storm we previewed last week. The coronal mass ejection that prompted NOAA's G1 watch for October 2 passed with barely a ripple: NOAA's daily indices show October 2 as one of the quietest days of the month, with an estimated planetary A-index of 3. The watch renewed on October 1 had already added a second G1 day for October 4, citing the coronal hole, and that is the part that delivered, one level higher than predicted.

How Sunday compared with the quiet week before it

NOAA's daily geomagnetic indices make the jump visible. The estimated planetary A-index, a daily average of magnetic disturbance, sat between 3 and 4 from September 28 through October 2, rose to 7 on October 3 as the first edge of the stream arrived, then leapt to 36 on October 4. The highest three-hour estimated Kp on Sunday was 5.67, which rounds to the Kp 6 that triggered the G2 alert.

On NOAA's scale, G2 is the level at which auroras have been seen as far south as New York and Idaho, which matches this weekend. EarthSky's sun news for October 5 ran a webcam snapshot of the aurora over Lake Vermilion, Minnesota, at 10:43 PM local time on Saturday, and Spaceweather.com reported displays photographed from New York to Iowa during the two-day event. Both are secondary reports; NOAA's data is the primary record.

What comes next

NOAA's three-day forecast issued at 8:30 PM ET on October 4 expects a brief return to G1 in the first hours of Monday (Kp 4.67 for the 8 PM to 11 PM ET window on Sunday night), then a steady decline: Kp no higher than about 3.7 on Tuesday and under 3 by Wednesday. The 27-day outlook issued early Monday puts the largest expected Kp at 5 on October 5, 4 on October 6 and 3 on October 7. Auroras are possible again on Monday night only at the northernmost latitudes. The sun itself is quiet: five small sunspot groups, the strongest flare of the weekend a B9, no Earth-directed CMEs in coronagraph images.

What it means spiritually

Facts first: a coronal hole stream is fast solar wind, a G2 storm is a moderate disturbance of Earth's magnetic field, and nothing in the NOAA products describes effects on people. The research on whether solar storms touch the body is thin, as we laid out in our earlier piece. What follows is tradition and interpretation.

The weekend's story has a shape that sky-watching traditions would recognize. The event everyone was told to expect, the CME, arrived as nothing. The event almost nobody was watching for, a hole in the sun's corona quietly streaming wind, delivered the lights. In the old reading of the aurora as a visitation, this is the lesson of the unannounced guest: what you prepare for and what arrives are rarely the same thing, and the second is often the more generous. That it happened in the first week of October, as the Wheel of the Year leans toward Samhain and the waning Moon moves toward the new Moon of October 10, gives it a seasonal note of release. Something old emptied out, something unexpected filled the space.

What you can do now

• Check tonight, not tomorrow. NOAA's 30-minute aurora forecast shows the live oval; Kp 5 is the G1 threshold. The chance fades each night this week.
• If you photographed it, keep the timestamp. Saturday and Sunday night images are a record of a storm that outran its forecast. Note the time; it helps you match your sighting to the Kp alerts above.
• Use the fade as a release week. The Moon is waning toward the new Moon on Saturday, October 10. A short waning Moon ritual fits the storm's own decline.
• Keep expectations small. Monday's forecast tops out at G1 and only early in the night. Enjoy a glow if you get one; most of the country will not.
• Set your alarm for Tuesday instead. The same predawn sky brings the Moon covering Jupiter on October 6, visible across most of the eastern and central United States.

Pairs well with: Labradorite Comfort Stone, the stone whose flash of green and blue is traditionally compared to the northern lights.

Sources

• NOAA Space Weather Prediction Center, Alerts, Watches and Warnings: ALTK06 serial 726 (G2, Kp 6 reached 2026 Oct 04 2057 UTC); ALTK05 serials 2050 to 2054; WARK05 serials 2267 to 2269; WARK04 serials 5424 to 5426; WATA20 serial 1128 (2026 Oct 01 1428 UTC). swpc.noaa.gov/products/alerts-watches-and-warnings
• NOAA SWPC, Forecast Discussion, issued 2026 Oct 05 0030 UTC (positive polarity coronal hole high speed stream; Bt peak 22 nT; Bz -20 nT at 04/0611 UTC; speed peak ~644 km/s at 04/1807 UTC; G2 reached). swpc.noaa.gov/products/forecast-discussion
• NOAA SWPC, 3-Day Forecast, issued 2026 Oct 05 0030 UTC (greatest observed Kp 6; expected Kp 4.67 early Oct 5). swpc.noaa.gov/products/3-day-forecast
• NOAA SWPC, Daily Geomagnetic Data (estimated planetary A-index Sep 28 to Oct 4) and 27-Day Outlook issued 2026 Oct 05 0139 UTC. swpc.noaa.gov/products/27-day-outlook
• NOAA Space Weather Scales (G2: aurora seen as low as New York and Idaho). swpc.noaa.gov/noaa-scales-explanation
• EarthSky, "Sun news: Coronal hole winds caused auroras last night," C. Alex Young et al., October 5, 2026 (secondary; Lake Vermilion, MN webcam image). earthsky.org
• Spaceweather.com, Dr. Tony Phillips, October 5, 2026 (secondary; "weekend aurora outburst," photos from New York to Iowa). spaceweather.com
• U.S. Naval Observatory, Phases of the Moon 2026 (New Moon October 10, 15:50 UT). aa.usno.navy.mil
• Questions about an order or a product: 28@templeofdesire.com

The spiritual readings in this article are tradition and lived practice, not scientifically proven. Space weather changes by the hour; check NOAA before you drive anywhere.